Butterflies may struggle to survive because of longer and warmer autumns caused by climate change, a new study has suggested.
Researchers said hotter temperatures across Britain will make the insects less likely to turn into adults, after exposing them to a variety of conditions in lab experiments to test the theory, according to The Daily Mail.
Green-veined whites – common across the UK – fared best when subjected to milder simulations, while their chrysalises lost more weight and used more energy under warmer and longer autumn conditions.
This, the researchers at the University of Stockholm said, made the butterflies less likely to survive winter and emerge in spring.
Lead author Dr. Matthew Nielsen at the University of Oulu, Finland, said: “We show stressful conditions experienced at one time of year can have lasting negative consequences at other times of year.”
Last autumn, Britain was hotter than the Algarve with temperatures reaching 75°F (24°C) at the end of September.
“Climate change is making autumns warmer and last longer. It was this specific combination of conditions that had the greatest impact on the butterflies in our study,” Nielsen added.
The butterflies didn't die immediately under the more elevated conditions but were less likely to turn into adults. Once a caterpillar stops eating, it hangs upside down from a twig or leaf and molts into a shiny chrysalis.
Animals that enter a dormant stage through the winter are especially vulnerable to warming because it raises metabolism and causes them to run out of energy faster.
“Even though dormant animals use less energy than active animals, they use more when it is warmer, and they can't eat to replace that lost energy,” Nielsen added.